SPARK PLUG INDEXING-DOES IT REALLY ADD HORSEPOWER? JUNKYARD LS MOTOR MYTHS! LOW $ MODS-DOES IT WORK?

WHAT THE HECK DOES INDEXING A SPARK PLUG MEAN? CAN YOU INCREASE POWER BY INDEXING SPARK PLUGS? SHOULD YOU EVEN WORRY ABOUT IT? HOW HARD IS IT TO INDEX SPARK PLUGS? WILL IT ADD MPG? CHECK OUT THIS VIDEO WHERE I STARTED WITH A BTR-CAMMED 5.3L L33 EQUIPPED WITH A FAST INTAKE, THEN INDEXED THE PLUGS SO THEY ALL AIMED AT THE SAME SPOT ON THE COMBUSTION CHAMBER. I THEN AIMED THE OPENING OF THE ELECTRODES OF ALL PLUGS AT THE INTAKE VALVE. I THEN DID THE SAME WITH ALL THE ELECTRODES AIMED AT THE EXHAUST VALVES! WAS THERE ANY POWER GAIN FROM ALL THIS WORK? CHECK IT OUT!

[@TT-io8dl]

Richard is as powerful as Google. If you have a question, argument, or doubt when it comes to something with a crank and pistons.....Richard wont just do like everyone else and argue their opinion is right. This man goes to great lengths to show the answer. Keep up the hard work brother.

[@disolejunk]

Steve Morris engines

[@Airman..]

Rich is a Performance lie detector

[@jonathonlyles3349]

This man is the project farm of engines

[@dynodon100]

The reason that we did that in the 60's and 70's is the pistons had domes and they MAY come in contact with the pistons.That was all. We marked the electrode side (the arm) and if we could see it up we were ok. Not all spark plugs would start the same place. so we had extras. Yes I am old and still building...and racing.

[@Peter-V_00]

That's what retracted gap plugs were for.

[@dynodon100]

@@Peter-V_00 We tried them in auto school and the shrouded spark just left us flat.That was in the 70's a long time ago.

[@79huddy]

Yep had to straighten out a 402 chevy in a mud truck buddy did a tune up after buying it and everything went to hell blew the headgasket too turns out it had a 5-7 swap cam and 14 to 1 compression when I got the heads off it had some real nice ross dome pistons in it

[@heavymetalmadness666]

I ran into an engine with compression washers on two of the spark plugs (V8), and thought" what was that about". It was about not having the piston dome hitting the spark plug electrode! Rather than going through a bunch of plugs to find ones that cleared they used compression washers to get a bit more adjustment on the indexing. Clearly a bad choice of dealing with the plug clearance issue, and once some engines bounce around from owner to owner you can't get that critical information. That engine wound up getting the same plugs that were in in and one or two got smashed, because who would have thought?

[@heavymetalmadness666]

The way it seems the aftermarket claims go.... Indexing the sparkplugs can gain more than 400 hp...well yeah if you went from 7.5 compression ratio to now 14.0 or more and must!

[@sbfguy7793]

I always find it interesting how you can show people video proof of how something works or not, and even then, they will still hold their same opinion. Fascinating humans.

[@karlmoltzan6196]

Great test. I am 64 and remember reading that the only reason for indexing was for piston clearance on high dome pistons.

[@richardholdener1727]

that's when I do it

[@danielwilson6665]

I can remember 64 🤔. Indexing for proper clearance verification always makes sense. I would also try to have the spark fully exposed to the intake charge rather than positioned with the side electrode blocking a clear line of sight between the incoming charge and the full spark. It’s mostly a compulsive thing to do because there couldn’t be much horsepower left to extract.

[@karlmoltzan6196]

@@danielwilson6665 it can not make a difference in power because both valves are closed at the time of the spark.

[@danielwilson6665]

@@karlmoltzan6196 ….. I would hope so but I mentioned it to point out a different train of thought about the subject. Thanks.

[@rtkl13]

​@karlmoltzan6196 so what your saying is that the mixture is standing still when the valves are closed ?

[@GroovesAndLands]

A decent bit of work went into this. Thanks for doing it.

[@TomGlander]

This is where German engineering shines, because my Mercedes CLS63 AMG has indexed plugs from the factory... all the threads begin at the SAME place on the plug, and after torquing to required spec... all the plugs are indexed. It's like magic. Does it really make a difference? That's up for argument.

[@JetBlackmf]

I indexed my blown 351 Cleveland , no noticeable difference in performance. Indexing removed the OCD feelings I had. ;)

[@watsisbuttndo829]

The only time I've had to index plugs is on one of my race bikes where the piston runs so close to the plug if you over rev it with the plug strap in the down position the piston would tap it and close the gap.

[@mickgrimes9078]

was looking forward to this one! thanks for putting in the hard work.

[@philthelawnman]

Watching NHRA on Sunday I remember they index the plugs so I also started doing it in the late 70s. Well here I am almost 54 and still index all my plugs. Now I will never spend that time again. Thanks.

[@elmerfudpucker3204]

The only time I ever indexed all the plugs was on one engine, back in the early 80s. We were running 17:1 comp. ratio on a short deck Cleveland engine with Wiseco pistons that had a pretty close clearance between the piston dome and the plug electrode. The pistons had a divot for the plugs, but it was still pretty close. We felt that running a spacer on the plugs was cheap insurance, and since we were doing that, we indexed the plugs in the process. Never had a problem, but the driver never noticed any difference either.

[@brianmorris9584]

Great video rich, you do all the research, we get all the knowledge

[@Super-Dave-Outdoors]

I had thought about plug indexing last week when i had an engine apart at work. I figured it didnt matter but I was still curious. Thanks so much for all the work you put in testing!

[@videomaniac108]

Thank you, Richard, for your fascinating and informative videos. They are exactly the things I would like to be doing if I had the money and time to be testing ideas out on engines.

[@joels7605]

This is something I've wondered about for 20 years. This video scratched that itch. Thank you.

[@mongoose60ft42]

I love the pull from room to room. Love this guy

[@joelgilmer45]

Spark plug indexing myth busted! Outstanding video Richard.

[@Akestler]

This was a neat test. I've never heard of indexing plugs

[@niall21]

Learned about this topic today, thought you'd have the answer with some testing, and now I'll just forget about it :) Thanks!

[@obbyjep7597]

Good info thanks. The times iv indexed the plugs was to clear dome pistons with heads like vortecs. Never knew if there was power to be gained otherwise

[@philllsxga.7737]

I have a SKI Doo snowmobile. It has a direct injected two stroke Etek. It gets 20 miles per gallon on the trails.. It burns all the fuel injected into the cylinders.. You have to index the spark plugs.. There's three positions the plugs can be in the heads if you do not put them in per the manual you lose horsepower and MPGs...

[@blueyhis.zarsoff1147]

common on all DFI outboards too

[@ryanl8653]

I always thought indexing was BS, until I worked on a newer Porsche 911 that developed a CEL with misfire code in 1 cylinder after spark plug replacement. It did end up being an indexing issue!

[@joshmiller8663]

Great video Richard clears that myth up. Merry Christmas.

[@davesendit1348]

I honestly have never heard of this before, very interesting. Saw your Facebook post and came directly here to watch. Thanks!

[@richardholdener1727]

Welcome!

[@joseiracheta3817]

That test engine is impressive. The cam works very well

[@PenguinMotors]

well done Richard, its a test people have asked me to do, i dont have the patients and simply say its a waste of time

[@Jermo8115]

Haven’t done indexing but I went up in heat range and replaced old tires plug wires with low impedance wires and I feel like it helped. Could be a cool test since you seem to be on an ignition kick lately! BTW I’m running an lq9 w/706 heads and stock cam with no tune.

[@speakerville]

American Iron Magazine tested plug indexing many years ago on a stock 1200 sportster ( at the time, a stock harley was a dual fire ignition, both plugs fired at the same time ). they saw a 1.2 hp gain (2.5% increase) but the owner didn't care about the extra horsepower, she just LOVED how much smoother the bike ran at highway speed. As he said, it's all about application, and hoped for results.

[@davelowets]

Richard.. Your videos, at least for me, are much more interesting to watch when you include the dyno pulls that went along with the results that you talk about in the video. For a motorhead like me, I like to listen for the subtle changes in the engine sound when comparisons are made. Sometimes nothing can be descerned from the sound, but sometimes it's fairly obvious. The dyno runs are an important part of the whole process to me, and I surely welcome them into your videos. 👌

[@lewisfoltz6306]

As always, excellent video and content!

[@N-Lee]

A topic I have often long wondered about and wanted to know more !

[@royosborn7869]

Great video, Richard - thanks for running all these runs and posting the results - love your scientific methods and approach!

[@UglyasUbutFaster2]

Stock 1970 Dodge 440 with open Chambers head 906/452 and indexing the plugs for the ground strap was pointed at the intake valve allowed me to bring my total timing back from 44° to 40 degrees and I picked up just shy of a .1

[@casanovasmizzle]

Thanks for sharing your video. Ive always wondered about this. I think if the combustion chamber was less efficient maybe?

[@needmoreboost6369]

Great vid! And It’s definitely not worth the effort for the results you’ve shown! Especially on a low rpm n/a set up with a ton of spark, One thing I’d consider is even with out a significant gain on each individual plug, just by getting as close to even cycle on each cylinder should help smooth things out at higher rev’s and maybe more noticeable on single coil like you said. I’ve stopped indexing plugs on my turbo l36 for street not feeling significant gains but if I’m going to race it gets indexed just for piece of mind,wasted spark and boost find’s a weak spark

[@keysautorepair6038]

Been waiting on this video for a while thanks for doing it I think it makes a difference in my car before I watch the video I spend two hours indexing my plugs every time I change them hopefully I'm right.

[@thomashalley7258]

I've seen a article on indexing big bore stuff to help with a smoother idle cause the flame front would be the same in every cylinder.

[@gadd580]

Very good video...., it demystified in practice a theory that dates back to the 1950s. This is the case with high performance ignition modules , that promise to greatly increase the spark in the spark plugs , and there is no proof on the test bench whether they actually improve performance and fuel economy. To light a flame on our kitchen stove... *you don't need a blowtorch... just a matchstick.*

[@natelorimer8567]

Most indexing I seen was part throttle response and a tad of economy. I had more results from gap in economy. Never really noticed WOT difference. Although never tested at the track. This test confirms my suspicions.

[@eadgbefreak]

Saved money on shims and time. Thanks!

[@Sami-gs7qb]

Helpful tests thank you

[@shaneshane1379]

That is really nice to know. I always index and had engine that the dome would close the gap if I didn't index. As for a HP gain I'm glad to know indexing is BS. So all the good old flat top piston 350'S, YOU AINT GETTING SQUAT FOR NOW ON. 😃

[@jamesandannschmitt6835]

Back in the day, I ran circle track with sbc fuely heads. These heads had a circle impression or c-bore in the chamber under the spark plug. I used to index the plug directed at that stop in the chamber with the theory of having the flame front start there. In testing on track I found when I did that I would need 1-2 degrees more advance in timing. I couldn't run that same timing when not indexing toward the chamber. It produced higher end of straight away rpm's read off tatel tale tack.

[@richardholdener1727]

Needing more timing is a sign of inefficiency and I would like to see a real test

[@pheonixfps9248]

Hey Richard, we used to index for smoothness. 1 hp, it's still something, but the smoothness of the engine, especially for things like Rb's, JZ's, Coyote's, ect being boosted, quad cam and high compression in some cases, helped with smoothness of engine vibration, and helped with better tuning, because it created consistency in timing, and eliminated ms in flame development. Especially important on 8/9/1000+ engines. Fuel economy does benefit slightly too on some engines because of the factory tuning.

[@richardholdener1727]

Define smoothness-what does it change-because it was not power. I'd also like to see 1000-hp turbo Rbs or 2Js or even Coyotes that test consistently to 1 hp.

[@pheonixfps9248]

@richardholdener1727 I thought I did? I can't say we bothered looking at dyno information of power differences between indexed and non indexed, rather we where just looking at egt's and vibration of the engine. Engines just seemed happier with them indexed towards the intake valves/injectors and ran smoother because of consistency between the cylinders. Probably the other thing to note in our findings was low engine rpm taking off from lights/stops, manual vehicles seemed happier with throttle response and smoothness rather than being a little jerky/shudder. I think the dyno only tells one part of the tale, seat of the pants/on road tells the other, just in my experiences. I also wasn't saying any of those engines test to 1hp each time?... i was merely referring to the smoothness of noting to the indexing.

[@chrisyeahbuuwassrileegowyn9279]

You earned your money here Richard....

[@danwiththe8647]

Thanks for the video, I've always heard rumours about indexing providing small gains when it comes to heavily controlled low power setups (one make races etc. like the Excel series here in AUS). where you're trying to squeeze out every possible horse power you legally can. this test also got me thinking about the depth at which the plug enters the combustion chamber as shimming them moves them further out of the chamber, surely this is as negligible as your tests have shown indexing to be for this sort of set up. wont waste time with indexing and will just make sure it has a solid ignition system

[@richardholdener1727]

THERE IS NOTHING TO SQUEEZE

[@bdugle1]

Any comment about switching to E3 plugs? I seem to remember an Engine Power episode that showed a small gain. Thanks for another interesting video Richard!

[@Lance.West4]

Wish I had this info back when I was racing Late model stock... My crew chief and engine builder made us index and it's so tedious to get it right. I always knew in the back of my head this might be 1/2 hp... But in a class where you can run any lift flat tappet cam, bowtie heads, restricted down to a 500cfm, 2 barrel 5 hp was the difference in qualifying 1st or 20th. The engine builder was one of the best & well-known in NC, and NC has some of the best. I think they just wanted to mess with me I was only like 21.

[@toomanyunlearned1]

From what I see in order to properly index you can’t shim them with washers or spacers. This robs power by setting the electrodes too far in or out from the correct positions. So the minimal gains could have been robbed by the improper electrode depth. Also a variation is tunes have been noted to gain results. Just something to consider.

[@richardholdener1727]

there is no need to change the tune with different plug indexing. Also, we showed that changing the projected tip vs non showed no change in power so your theory on washers in not accurate. On this motor, indexing did nothing.

[@YerkitRacingChannel]

Awesome! Thanks for sharing! The performance world needed this. I just did a video on indexing on my channel. Did a ton of research on which direction was best. Ended up pointing at the exhaust valve for the heck of it but figured it would yield any gains. Only time it is really critical is with high dome pistons where the strap needs to be in the notch of the piston.

[@btchhopperou812]

OK, so the indexing deal is kinda not really worth doing... BUT, I'm VERY impressed that you have that L33 junkyard mill kicking out pretty close to 480HP by swapping factory parts for 1 7/8" headers, FAST intake/TB and a BTR cam. To me, that is quite inspiring but at the same time, I'm beginning to ask myself a lot of questions about the economics of my current 'build' LOL. Thanks for getting to the bottom of this debate Richard, I believe it was time well spent.

[@michaelblacktree]

Does your engine seem a little... recalcitrant? 😛

[@btchhopperou812]

@@michaelblacktree 🤣🤣🤣

[@davidciesielski8251]

Thanks, I often wondered about this.....

[@julesguedry2466]

Sick intro as always

[@63turbo]

If some engines gain some power from indexing, it would HAVE to be because something about the heads doesnt promote good mixing and turbulence, but when the plugs are all aimed the same, theres a slightly better chance of lighting off a rich portion of the charge. I would bet that indexing would also probably help more in low spark energy systems than ones that have higher energy. The other possible effect from plug indexing may be to diminish ping sensitivity when ideal indexing is used vs increased sensitivity to ping when the worst indexing is used. It might also be that the way one could measure that is to see if the best power ignition timing changes at all vs plug indexing!

[@Sleeperdude]

Good information

[@martygrajeda3457]

Always informational.

[@LimitedGunnerGM]

I did it on my Tacoma, because my Ripp coils are known to cause a big of preignition at low RPM’s. I’ve never had a problem since.

[@SentinelPrime13]

I index them on my 408 based on article i read on all cylinders blog but i never dynoed it. Was alot of work.

[@blitzfreak4875]

I can tell you the truth that happened to my street 75’ Camaro, after installing a shift kit. It would not chirp/squeal the tires. I read an article about side gapping the spark plugs. After that, it would squeal the tires after shifting to the next gears. So some type of improvement was definitely happening. What happens on the Dyno, doesn’t actually mean what happens at the drag strip. Quote from “Warren Johnson”.

[@richardholdener1727]

wrong-if it makes more power at the track-that shows on the dyno-it doesn't EVER happen in just 1 place unless you changed something. side gapping only helps if you had a misfire without it

[@button-puncher]

I always wondered. Thanks Richard. I'll admit, I'm still going to try it on my Onan generator. It's a 1.0L horizontally opposed two-cylinder with flat heads. I figure pointing towards the cylinder *should* be better than pointing at the back of the pocket. For me it's about efficiency (fuel economy). If I can get an extra 10-15 minutes of runtime out of a 40lb tank, well, that's better than nothing. BTW, it makes a whopping 14HP at 1800rpm. :D

[@richardholdener1727]

Did it work?

[@robertcranwell7847]

Richard, I remember 30-years ago Jacobs Electronics/Ignition was big on indexing and their hot ignition boxes that had you open the gap on spark plugs for more power.

[@richardholdener1727]

I REMEMBER THEIR DOG AND PONY SHOWS WHEN THEY WOULD COME TO THE MAGAZINES

[@pittsky]

This is the video I have been waiting for.

[@michaelspiering7585]

That was really informative.

[@3800S1]

When I was building my engine I indexed them because why not, cost me nothing as I got them all to aim to the chamber center just by swapping them around to the right cylinders until they were all in the preferred direction. I also doubted they did anything by hey, now I know.

[@marvinhindman1790]

I knew it! My little gain on plugs was gulping to E3 plugs. 5hp gain and 5 years of reliability too

[@richardholdener1727]

5 hp...? no

[@atheplummer]

30 seconds in and my initial thoughts are, indexing spark plugs doesn't make anymore power. I will say though, I have a 468 BBC with 13.5:1 compression, 781 open chamber heads, with high dome pistons. On that engine, I had to index the spark plugs, because if I didn't, the piston would get to TDC and shove the ground strap tight to the electrode. The ground strap at .30 would hit the piston!!!. That's my initial thoughts on indexing. Let's see.

[@jb333zy3]

You should experiment with exhaust length with x pipe vs h pipe cat back delete or 02 sensor location hp gain or loose best placement for ls motors

[@scottsoper2739]

Great ignition tests but wondering if you've done a test to determine hiw an MSD ignition affects power.

[@nrgzrbunny7775]

Damn, Richard got into like 4th gear on the way to the dyno cell @4:50

[@vGamBIT]

On the 10:52 in video spark plugs are from different brands that might be an issue with the experiment. Also spark plug indexing makes more effect on idle and low RPM applications till 2000-2500 as duration of cycle is much longer that is on mid and high RPM. Also it's depends of combustion chamber configuration in head and piston. Saw test of small crappy Lada 21083 1.5L engine (2 valves per cylinder) and it's fuel consumption on low loads and 3500 rpm can vary up to 15% and also up to 80% in emmisions . They also tested the "bad indexing" when spark all 4 spark plugs were pointed to the cylinder walls and reported that has very bad idling up to 1200 rpm (normal idle 800-900 rpm for this motor)

[@richardholdener1727]

we saw no change in idle, the tested using 8 mismatched plugs (from the junkyard) against 8 new ones-also no change in power

[@vGamBIT]

@@richardholdener1727 In power may be no changes but part load, idle and throttle response are affected, especially on street engine because of different wear of electrodes and foiling. Try on something smaller like inline 4 engine where much more imbalances by design and you will notice the difference. More crappy spark plugs on high compression NA engine or turbocharged stop firing after some level of pressure and revs.

[@richardholdener1727]

I have run many, many tests on plugs on 4, 6 and 8 cylinder combinations, there is no power if the plug is firing. If part load or throttle response (which is power) were changed, we would see it. Look elsewhere for power.

[@slowcountryboy476]

Geeze lueeze, I was getting ready to go out and increase the plug gaps to .100 as you showed in the other video until horse results came in at about 4 or 5 to 6 horse!! Not really worth it at this time. Maybe when I replace the plugs. However, I did round off or "bullnose" the side electrodes pursuant to David Vizard's recommendations. I can feel a bit of extra power/torque and the engine runs smoother. I will continue the practice in future tunes.

[@richardholdener1727]

you do what you feel is right

[@georgedreisch2662]

Great analysis and video! Now I’m wondering how much time I pissed away back in the day…😂

[@sirtnfol8476]

Been waiting for this one

[@KaLeB_]

nice, tks. I think the washers masks the result a little bit because they take the electrodes tips out of the center of the combustion chamber, with is the opposite of the projected electrode plugs do. it's not a big deal, but the thing is to find a plug that gets indexed without any extra washer, maybe swapping them from one hole to another till get the higher as possible of them indexed. what if you 'd try with the projected electrode plugs? ( just adding the letter P do the plus youre using right now, as long they don't hit anything inside...you gotta roll the engine by hand to find out if it's possible befere trying...I fell that those plugs increase the torque and the engines overall response.

[@richardholdener1727]

we swapped plugs from hole to hole-no change

[@refgarcia8218]

Hey Richard could you and please do a FORD 460 EFI? 1988-1997 found in the F-250-F350s. There was two different head sets available the early E7TE and the later F3TE with in those years. There was a little difference in the heads. Also the early EFI was Speed Density vs the later was MAP. Most people interested I would imagine are going to emphasized on the Torque side for pulling. There is just NOT much about it on the Net at all when it comes to this specific EFI set up specifically using and retaining the EFI. Anybody can change the top end of the engine with after market heads and add a carburetor but that is not what I and I'm sure a few more people would like to see. I have seen questions posted about this set up but not much of a solid response on what can be done or has been done to get more pulling power. Thanks in advanced. GREAT JOB WITH THE CHANNEL.

[@creverett9]

WOW!! look at that old school toughbook!!

[@scottatkins8968]

Agree with everyone else! Keeps the larger domes from forcing you to buy more of these expensive plugs 😂

[@kstricl]

I had heard about stock car racers were getting a few extra hp from indexing back in the 90's (80's 350's) and wanted to try it. I had a turtle back Caprice (91) with the stock tbi 305 and indexed the plugs when I tuned it up. I aimed it towards the center of the chamber on the theory that the flame front wouldn't need to curl around the chamber. Didn't really notice any power gains that couldn't be accounted for from new properly gapped plugs, but I used to get phenomenal fuel economy on long trips with that gutless car. Even moved my family with a 6x12 uhaul trailer behind it over mountains. If there truly were gains on my part, I would attribute it to the fact that it was NOT an efficient chamber design, with a (relative to the ls) low power 90's single coil ignition that needed every little bit of help and the style of plug on that head meant I didn't accidentally shroud the electrode. I currently have a tbi 350 in my 95's chevy suburban, and I just shoved that porcelain goodness straight in after checking that gap and didn't even think twice. Power and economy gains on that thing would be best served by taking the massive meats off and going back to a stock, lighter tire...

[@shawnlibby675]

Yeah just think a lot of it was just race talk back then today people have dynos everywhere instead of using the butt dyno..... a lot of race talk about little tricks that were a lot of them didn't a lot of them had no evidence Richard Holden puts out the evidence by using that dyno... so a lot of our race talk for the 80's and 90's some of the stuff about indexing was took wrong the whole thing about it is someone could do this in the garage without a Dino and the car was still run good either way so you put your car and it's running good you do this track index the plugs start car back up it still runs good drive up the road yep it's running and they going think that if an upgrade because it ran just like it did before but they can't tell the difference because there is no dyno.. evidence to a lotta little race tracks back then some of the race tricks for authentic in some of the race tricks for just BS... but this is where Richard holder comes into play in the 2000s LOL he does all kinds of homework for us with test results

[@bcbloc02]

Should have tried it on a big block Chevy with a points ignition. Maybe then it would show up but ultimately I think unless for some reason it was effecting the spark generation then it would not matter as every orientation is going to ignite the fuel. Probably more hp difference from changing heat range plugs than indexing.

[@ottopartz1]

I've always been under the impression that indexing only makes any difference on two stroke engines where the plugs encounter airflow and ignition at the same time. Plug strap should point away from the intake valve in that application so it doesn't shield the spark from the fuel. Although I wasn't competitive enough to mess around with a bunch of shim washers.

[@jimh4167]

Probable would make a bigger difference. On an early motor with coils that produce orange spark

[@adamdozier5757]

Wish you would've ran one more test with a back cut plug. Did you Ohm the plugs before you started would be my next worry? Tests never end just brings up more questions. LOL

[@PANTYEATR1]

Wow, this is very interesting... So i wonder where this process came from and why did anybody ever think it made power? 🤔 Thanks for the video Mr. Holdener🏆

[@PANTYEATR1]

@@bigboreracing356 awesome clarification, thank you💪

[@nicholasabbott2457]

I thought indexing plugs was only for older engines like small block Chevy and big block Chevy. Primarily so the piston wouldn’t contact the plug but for more high horse power applications. This will be a cool video to watch though.

[@The_Fat_Turtle]

Had to pull the head off my L96 6.0L because a spark plug blew out the threads (first time that's happened to me on an LS motor) and was going to index them before throwing the heads back in because it makes sense in theory. Glad you put out a video with the actual answer.

[@adamdodsy84]

Ford's new engines all come with indexed plugs. Designed in a way that they pretty much can't be installed out of index. Pretty cool. Maybe makes a bigger difference on DOHC or Hemi? Maybe slightly reduces emissions?

[@adamdodsy84]

kzbin.info/www/bejne/qJDdnnRshpWWh5Y

[@EdgarsLS]

I index the plugs just to make sure they're all in a more optimal angle, not to expect any power increase but instead make sure there's the least change for misfires or any other problems

[@ronb113]

I’ve always been curious about this

[@danielroque7183]

Cool vid

[@michaelblacktree]

A couple comments: 1) That's a pretty healthy dyno mule! 2) All that shim swapping must've been tedious.

[@theshed8802]

David Vizard did a video the other day that included a story about a 90hp swing in power on a Leyland Mini motor as a direct result of a spark plug change. What I gained from that is that electrode location is critical in that application. Likewise, I believe the same when it comes to indexing. In some applications it might be critical. But in most cases that it is, it is because of something else. Like poor combustion chamber design, poor piston design, poor atomisation in the cylinder etc. Good video Richard, thanks for doing it. Regards Greg

[@blow0me]

Impossible, because it would take a very good n/a A-series to make 90hp at all. Nevermind a 90hp swing ! lol You've clearly picked up something wrong. They're a very old, siamese port, typically 1300cc maximum engine. There is no way ever to see a 90hp swing unless it was from no spark plugs, and no power....and spark plugs and a running engine with 90hp

[@theshed8802]

@@blow0me go watch the video. It was supercharged. But seeing as you know everything before you even do any research, you must be smarter than Einstein

[@blow0me]

@@theshed8802 So where is this mythical video ?

[@dannytravis7118]

What I've heard is that the spark gap needs to be indexed away from the valves and down into the bore to supposedly make every cylinder have the same flame front on the top of the piston. From what I read in hot rod and David visards books is indexing the plugs are only worth about 1 to 3 hp. So in a daily driver you won't notice any difference however in a Nascar or nhra top fuel division that extra 1 to 3 hp could mean the difference between first and second place. I've watched nhra funny car races where they completely tear down the motor and rebuild it between rounds and have never seen them bother with indexed plugs. I've heard those nitro methane engines make about 10000 hp so I reckon 1 to 3 hp isn't an issue. I don't believe it's enough difference to make a difference unless it's an extremely narrow application like Nascar or modified dirt track racer or maybe pure stock where your goal is wring out every available hp.

[@BOOT]

The way I was taught to index plugs is buy extra like a box or two, mark them all and find what cylinder that a plug points where you want. No washers required! DV says it doesn't help really until high compression(not talking dome pistons). In my opinion it sometimes helps part-throttle, not something you can feel/test on the engine dyno

[@calebnezat8418]

Junkyard i6 ford! The efi motors aren’t too hard to find there is no good documentation for it.. I’d like to see you try to find that motors limit and publish it!

[@officeassistant1292]

Hi Richard you should test some Granatelli spark plugs wires they claim lots of horsepower over stock wires....

[@richardholdener1727]

NO POWER IN WIRES IF FUNCTIONING CORRECTLY

[@rustybritches6747]

I'm going to take a guess, an educated guess because I've tried this, that it doesn't make any difference at all! using indexing washers on the plugs is going to change the combustion chamber CC/volume by moving the plug further in or out of the combustion chamber which I would expect uneven power from cylinder to cylinder!

[@laiky71]

Looking at that plug from the combustion chamber side. It looks like a turtle hiding it's head. I wonder what an extended tip plug might do in this application.

[@Shofear69]

Indexing made a huge difference on the older Taurus sho engines....

[@curlracing276]

I would like to see if there is a difference on a boosted engine (turbo/supercharger) with a single coil. Kind of like would if make a difference indexing spark plugs in a worse case scenario. Re test please.